Experiment: modify .travis.yml travis_wait

Modify the command as per https://docs.travis-ci.com/user/common-build-problems/
in particular don't try and run it as a separate command.

Author: akgrant43

.travis.yml

@@ -21,5 +21,4 @@ before_script:
   - mkdir -p $SMALLTALK_CI_BUILD/UCD && cp UCD/* $SMALLTALK_CI_BUILD/UCD/
 
 script:
-  - travis_wait 120 sleep infinity &
-  - $SMALLTALK_CI_HOME/run.sh ${CI_FILE}
+  - travis_wait 60 $SMALLTALK_CI_HOME/run.sh ${CI_FILE}